哪位帮我看看用JSP写的代码是哪出错了

<%@page contentType="text/html;charset=GB2312"%>
<HTML>
<%!Hashtable hashtable=new Hashtable();
     public synchronized void putString(String s)
     {
         hashtable.put(s,s);
      }
%>
<%  String person_name=request.getParameter("name");
       name_found=(String)hashtable.get(person_name);
       if(name_found==null)
       {
          String person_email=request.getParameter("address");
            if(person_email==null)
            {
               person_email="";
             }
         String Tokenizer fenxi=new String Tokenizer(person_email," @");
         int n=fenxi.countTokens();
         if(n>=3)
          {
            out.print("<BR>"+"你输入的email有不合法字符");
            }
         else
          {
             putString(person_name);
             out.print("<BR>"+"您已注册成功");
             out.put("<BR>"+"您注册的名字是"+person_name);
           }
        }
       else
         {
           out.print("<BR>"+"该名字已存在，请您换个名字");
          }
%>
</HTML>

追问：
        	
				报的错，我已经贴出来了
问题是用jsp写的还用导入包吗？
	            
	            


			
            
            
        
        	
				当然要导入包啊，你难道用java写不用导入包的吗
异常An error occurred at line: 3 in the jsp file: /login2.jsp
Hashtable cannot be resolved to a type
就是报的3: <%!Hashtable hashtable=new Hashtable();这行的错
	            
	            


			
            
            
        
        	
				但是还是有错，你能帮我把这篇代码改改吗？
An error occurred at line: 11 in the jsp file: /login2.jsp
name_found cannot be resolved to a variable
8:       }
9: %>
10: <%  String person_name=request.getParameter("name");
11:        name_found=(String)hashtable.get(person_name);
12:        if(name_found==null)
13:        {
14:           String person_email=request.getParameter("address");
	            
	            


			
            
            
        
        	
				name_found=(String)hashtable.get(person_name); ,你name_found这个变量都没有声明啊。
	            
	            


			
            
            
        
        	
				你能接着帮办我看看其他的错误吗？我刚学有好多不明白的地方，非常感谢！
An error occurred at line: 20 in the jsp file: /login2.jsp
Syntax error, insert ";" to complete LocalVariableDeclarationStatement
20:          String Tokenizer fenxi=new String Tokenizer(person_email," @");
	            
	            


			
            
            
        
        	
				20:          String Tokenizer fenxi=new String Tokenizer(person_email," @");
这行【new String Tokenizer(person_email," @");】改成--new StringTokenizer(person_email," @");把空格去掉。。StringTokenizer就是一个类，多打个空格就语法错误了
	            
	            


			
            
            
        
        	
				我试了，还是有错
	            
	            


			
            
            
        
        	
				StringTokenizer fenxi=new StringTokenizer(person_email," @"); 前面那个也一样啊 ，把空格去掉。 - -！，劝你还是多看看java基础吧，这是基本的语法